Perhaps instead of saying "at best" they are con artists, it would have been more polite to say at worst, they are con artists. Probably many earnestly believe in what they are doing, and are just wrong.
I look back on the people I admired, and they questioned authority.
https://www.bloomberg.com/graphics/2015-doug-williams-war-on...
Calling them con artists is about as polite as I can be.
> And inadmissible in court in many places:
I'm not aware of any place that accepts polygraphs in a court.
"In the United States of America, (where polygraph testing is a growth industry) the admissibility of lie detector test results is determined by courts and legislators on a State by State basis.
In the Federal legal system, test results are inadmissible as substantive evidence. Whilst some States have allowed test results in criminal trials, States such as such as California have prohibited the admission of such evidence unless all parties consent to its admission."